v4.7.0

This release finishes what 4.6.0 started: RTF and HTML now carry the
same page-level behaviour PDF got last time (page numbers, facing
headers/footers, columns, keep-with-next, matching tabs/indents, Modern
spacing) — checked against a real word processor and a real browser, not
just our own PDF. Plus another round of printed-page fixes measured
against real WordStar 7 (auto-leading, print-time reflow, header/footer
timing, comment lines, form-feed formatting loss, the driver's character
substitutions including the euro), and a new MailMerge data-file reader.
Full itemized list in the CHANGELOG.

Measured against real WordStar 7: named divergences against real WS7
LaserJet printouts down from 10,576 to 3,682; 132 of 194 test documents
now print byte-identical to the original.

Known limit carried forward: RTF columns/keep-with-next/sections are
Printed-view only — Modern has no column model, by design.

Full changelog: v4.6.0...v4.7.0